A Magical Case
by moriartysweb
Summary: When Sherlock is sent on a case in Hogwarts, it is not only the wizarding world that dumbfounds him as he meets the genius Hermione Granger. Whilst protecting Harry Potter from Voldemort who is in hiding, he has to keep John unaware of his location whilst trying to abstain from Hermione.
1. Chapter 1

Sherlock's eyes lingered over Baker Street through the paned glass, the lids closing with boredom. He let out a futile sigh, breaking the selfish silence.

" Do you ever think that this world is so unbearably dull, that it must mean something better is beyond it...John?" He muttered, puffing up his cheeks to turn to John in apprehension, who was reading the newspaper contently.

" Woman with a beard won Eurovision, can't call that dull." He wittily remarked at his best friend whilst turning the page. Sherlock rolled his eyes and turned back to the window. Eurovision was his equivalent of torture, but he put up with it for John. A black car pulled up outside their house, catching Sherlock's interest immediately.

" We have a visitor." He announced, his voice dripping with anticipation, which quickly turned sour as he saw it was only his brother, Mycroft Holmes.

" So what's this about?" John asked, as Mycroft settled in his chair much to John's annoyance, having already served the group tea.

" Mr. Watson I'm afraid I'll have to ask you to leave, for this is a private and incredibly important matter. Perhaps your landlady will be free, or you can merely go to bed, preferably listen to your music with headphones on." Mycroft grimaced, wriggling in the chair and sniffing his nose. Sherlock looked up at John who stood awkwardly next to the pair of brothers.

" Right, cheers for that. I'll go see Sarah, think she's in." John muttered, grabbing his coat. Sherlock cocked his eyebrow, he thought Sarah and John would have broken up by now. He turned back to Mycroft and gave him a sarcastic grin.

" Brother dear, do tell me I'm practically buzzing." He drawled, wanting the god awful task over with so he could go to bed and let this boring day be over.

" Sherlock, this is going to be hard to understand-" Mycroft started.

" Me? Hard to understand?" Sherlock interrupted, acting like a child gleefully.

" Shut up, I'm the smart one. Now listen to me, there is a world other than ours, a magic world. It has it's own ministry, it's own people, and we to them are ' muggles '. I have been contacted by Albus Dumbledore who has requested you to teach at Hogwarts, their school, whilst working on a case there." Mycroft delivered with such a neutral manner even Sherlock was unsure if this was a joke.

" Mycroft, how long have you been dieting? We all know you get a little-" Sherlock teased, but that same curiosity was burning as Mycroft sighed and out of his briefcase, retrieved documents and photos. He handed one to Sherlock, of a magnificent castle, Hogwarts.

" You can see it's authentic. The case is to protect this boy, called Harry Potter. Recently, he has claimed an evil murderer, Lord Voldemort has returned. Their government does not believe him, you need to oversee him whilst having the day job of teaching Muggle Studies." Sherlock leaned forward in his chair, pressing his chin onto his clasped hands, it was an awful lot of information to take in.

" This is...impossible. How?! It's magic...Mycroft are you sure-?" Sherlock gestured with his hand in frustration, unable to comprehend this new world being laid out in front of him."

" You have my word this is real. Here are some documents, you'll be needing to find out a lot I assume. If you wish to take the case, here are your tickets." Mycroft lulled, handing over everything before making his way to the door. Before he left through the open door, he paused.

" Oh and Sherlock? Don't tell John." He added with a coy smile and left Sherlock sitting helpless. Throughout the night, he read page upon page about the wizarding world. And this boy, the boy who lived. How was he going to be any help? Every piece of logic in Sherlock's head told him this was all a hoax, but the burning desire for a chance at an extraordinary case was overpowering his common sense.

In the morning, John had still not returned. Sherlock regrettably had to leave a short note, explaining his absence as being a case in Ireland and that he wouldn't be back for a while. A small part of him felt guilty, as he didn't know when he'd get a chance to come back. In his blue and black shirt, he picked up his luggage and hailed a cab to Kings Cross Station, after a teary goodbye from Mrs Hudson.

" Platform 9 3/4..." Sherlock murmured to himself in disbelief, staring at the two signs reading 9 and 10 on the platform in confusion. This had to be a joke, Mycroft was probably hacking the CCTV right now and laughing his head off. Sherlock lingered on the concrete, not knowing what to do. Should he just go home and abandon this disaster? He was just about to leave when he spotted a familiar face from the photos, it was none other than Harry Potter himself, looking incredibly hurried. Sherlock pushed his luggage cart behind him, and just as the glasses wearing boy looked as though he was about to run straight into the pillar, Sherlock stopped him.

" Excuse me!" Sherlock shouted, causing Harry to turn around with a look of anxiety on his face.

" Yes?" He asked abruptly, he had other things on his mind. Sherlock had to remind himself this was the boy who no one believed battled a Dark Lord, or whatever.

" How do you..." Sherlock started, embarrassment taking over as he was supposed to be his teacher.

" Oh, the platform? Are you a teacher?" He asked, more polite than before. " My friends are already on-"

" Yes I am." Sherlock interrupted, then gave an apologetic glance.

" Right well you sort of just...run really. I know it soons bleak but really, that's it. Watch me." Harry said, and Sherlock watched as he ran right to- and then through the pillar as though it had swallowed him whole. Sherlock gulped, how hard could it be? He ran, feeling a little foolish, and closed his eyes when about to hit the wall- only to open them to the sight of the gleaming red Hogwarts Express. Harry was no where to be seen now, and Sherlock soon saw why as the train was about to leave. Pushing through crowds of teary eyed parents and relatives waving their children off Sherlock managed to put this stuff in the luggage compartment and bound onto the corridor of the train just as it was setting off. Sherlock stood tall over all the scrawny first years, and he made his way past the compartments, looking for a free one. He turned his head to see Harry sitting with a red-haired boy, sharing a laugh. Realizing he probably looked quite odd, Sherlock turned away and as he did- bumped into what looked like a bundle of books and frizz.

" Ow!" It exclaimed, and it appeared to be a girl, probably in her fifth year looking all flustered. Sherlock reluctantly helped to pick up her books.

" Oh my god your Sherlock Holmes." She said, much to Sherlock's surprise as they both stood up.

" Sorry?" How-" Sherlock asked, not knowing his internet fame had reached this world.

" I didn't know you knew about us..." She wavered off, her head somewhere else.

" I'm a teacher, actually. How did you know about me?" Sherlock replied quizzically.

" Oh, I'm erm... muggle born, I have muggle parents. I've heard a lot about the genius detective. You look less tall than in your photos." She flustered, and Sherlock couldn't help but roll his eyes at the common remark upon first meetings with fans.

" Well, good luck teaching Mr. Holmes." She says with a genuine smile, and then proceeds to enter Harry Potters compartment, apparently being very close. Sherlock lingered for a moment, wondering if she was Harry's girlfriend. He then spent the remainder of the journey on his own at the end of the train until it arrived at the glorious Hogwarts. Sherlock looked up at it in astonishment.

" This could be exciting." He said to himself with a grin.


	2. Chapter 2

Sherlock sat back in his chair at the head table, rejecting the mounds of dessert in front of him. Having just endured being introduced by the quirky headmaster, Dumbledore, he was perfectly happy to be silent for a while. Observing his co-workers, he couldn't help but almost gag at the sight of the Defence against the Dark Arts teacher, Dolores Umbridge. The toad-like woman was dressed from head to foot in pink, and had an expression of false superiority on her face, possibly hiding anxiety, Sherlock noted.

" Students, before you retire to your dormitories I would like to say, just one more thing." Dumbledore announced, having reached his stand without anybody noticing. He peered over his half-moon glasses at all the faces looking up at him. " With the return of Lord Voldemort, some of you may feel unsafe in these dark times. But I would like to remind you, you are in the safest premise of the wizarding world. There will be no Death Eaters coming for you in your sleep. Off you go now." Sherlock smirked as a rather plump and unfortunate looking boy's jaw dropped. Sherlock then realised who was sat next to the boy. Harry Potter, who though vigilant himself, had many dirty looks aiming at the back of his head from other students. Unable to comprehend the situation, Sherlock merely merged with the tidal wave of black cloaks and hats and made his way to his own room in the maze of a castle.

" Oh for god's sake, SHUT UP!" Sherlock bellowed, for the third time at Peeves, the trickster ghost he had the unfortunate luck of meeting. The ghost kept on entering Sherlock's rooms through the wall, singing rhymes then exiting before Sherlock could get him. How Sherlock would 'get' a transparent thing was the question whirring in the detectives mind. Deciding sleep was hopeless, Sherlock decided he would contact John. However upon arriving, a nasty looking caretaker named Filch took his laptop and blackberry off him, much to his protest. Apparently it was " policy for teachers as well as students". Instead, Sherlock headed for the owlery in his pyjamas and dressing gown.

A black furry ball greeted Sherlock as he opened the door, smacking right into his face. " What the-" Sherlock started, before realizing the ball was in fact a little owl, who then tried to start eating his fingers. Sherlock batted it away and shut the door behind him, then heard feet scuffle. Peering around, he saw Harry Potter stood awkwardly with a piece of parchment scrunched up in his hand.

" Hello, Professor Holmes." He said, his voice nervous. Sherlock edged closer to the snowy white owl next to him, who was nuzzling him in a loving way.

" Don't you students have one of those...curfew things." Sherlock murmured, admiring the senile creature.

" Yeah, the hushed whispers of my 'mates' was keeping me up." Harry confessed, triggering Sherlock's intrigue. Dumbledore had warned him, that he and Harry's claim the Dark Lord had returned was not taken so quickly by everyone, in fact most people apparently.

" So who are you writing to? Your family?" Sherlock breathed, hoping Harry would leave soon so he could write to John.

" God no, well sort of." Harry started, then looked to be cursing himself on the inside. " No, not family. A mate." Sherlock merely nodded and glanced at Harry's scrumpled up letter. It only took him a second to see this was no mate, scribbled handwriting with a nickname so obscure it could only be a cover up. Padfoot. Sherlock looked away, wondering who this was.

" Right well, see you in the morning Professor." Harry stammered, exiting quickly. Sherlock sighed and wrote the letter to John, explaining how well the case was going and how he would be gone for the foreseeable future of the year. After noting down Mycroft's address, so he could pass it onto the naïve John in the normal post, Sherlock stood aloof for a moment. He hated to admit it, but he was homesick.

The next morning, in the Muggle Studies classroom at 11:00, the fifth year students lazed about, dreading the next hour of boring facts about the muggle world they were so fortunate not to have to endure. Plus, they had just been introduced to Professor Umbridge, who had succeeded in depressing them about their upcoming, unadventurous lives completely, as well as humiliating Harry Potter about his Voldemort theory. All eyes were half-open apart from Hermione Granger, who's textbooks were piled neatly and who's quill was beckoning her to already start taking notes.

" Muggles, incredibly boring and dull people who by some odd coincidence, I have been a member for all my life up until now." Sherlock said upon arrival, and all eyes followed him as he made his way up to his desk. He set his briefcase on the surface then turned to his class, doing up the buttons on his suit jacket.

"Sherlock Holmes, don't call me Professor, it's an insult." He added, making Harry cringe for calling him that the previous night. Earning a few sniggers from the class, Sherlock picked up the textbook of Hermione's desk and flicked through it before tossing it in the bin.

" I hear it is your O.W.L.S this year so we won't start wasting time now with these-" Sherlock stated.

" Ey, different from the witch isn't he?" Sherlock overheard the ginger, freckled boy sat next to Hermione Granger murmur as he slouched over his desk with a bemused expression on his face.

" The witch? Aren't all the females here witches?" Sherlock frowned at him, as the boy named Ronald Weasley turned red as the class attention turned to him.

" No, I mean yes. But Umbridge is a real..." He stammered, as Sherlock's eyes bore into him.

" I think bitch would be a more appropriate term than witch here Mr. Weasley, we don't want to upset any of your lady friends." Sherlock smirked, glancing back at Hermione who's chin was raised to high it looked as though she was balancing invisible books on it. An hour later, the students were filing out, giddily talking about their controversial new teacher on their way to dinner. When making his own way back to his room so he could read John's letter, Sherlock bumped into Umbridge in the corridor.

" Ah, Sherlock Holmes isn't it?" She smiled, the grin reaching higher than what was trustworthy. Sherlock smiled, confirming she had the right man without offering any indication he wanted to have a conversation, but she continued anyway. " I've just heard the strangest thing, a muggle, teaching at Hogwarts? Dumbledore behind this, is he? Well, I'll be carrying out inspections soon, we'll see how long you last." Her grin turns even more sickly, and Sherlock notes how her voice drips with disguised contempt. He had no time for this awful hag, so he merely brushed past her and ignored her callings. Slamming the door of his room, he stalked to the bedside table and picked up the letter waiting for him. Opening it, he read carefully to hear how John was.

Sherlock,

Where is your phone? Or your laptop? Never did I think I'd be buying over-priced stamps to speak to you. Work is keeping me occupied, and I'm at Sarah's quite a lot. When are you coming back? Why can't I know anything?

John

Sherlock sighed, John was writing to him how he thought he should to one such as Sherlock. Short, brief. But that wasn't what Sherlock really wanted, though he'd never admit it, he needed to keep in touch with London, with Baker Street, with his blogger.

" Owls keeping you intact with your partner, Sherlock Holmes?" A wise old voice spoke out, and Sherlock whipped around to see Dumbledore, sat in the dark corner of the room on Sherlock's armchair. His eyes twinkled with entertainment, assessing Sherlock in a new light.

" I prefer texting." Sherlock muttered, turning around to put the letter back in the envelope.

" I'm sure you do, but people love to say more to fill up the page of a letter rather than fit on a screen, and I love people when they say more." He softly speaks, making Sherlock roll his eyes whilst thinking the wizard couldn't see him.

" What do you want?" He asked, getting straight to the point. Albus stood up and wandered over to stand beside Sherlock, looking out the window at the Black Lake.

" I fear I will not be here for long, soon Umbridge with the Minister of Magic behind her will push me out, and that's when I need you and your brother to step in. I came here to discuss-" Dumbledore started, before a deathly shriek echoed through the school, and the wizard did not hesitate in grabbing Sherlock's wrist, and apparating. Sherlock was pulled through another type of dimension and landed, feeling rather sick as though just off a rollercoaster, just outside Dolores Umbridge's office. The pair saw she had become some sort of cross between herself and a cat. With fur all over, and even a tail, she stood enraged.

" Dumbledore, what has happened to me?!" She shrieked, tugging her 'claws' at her fur. Sherlock noted Albus was trying hard to not laugh as well.

" Dolores, it has appeared your evening tea has been spiked with polyjuice potion, how much did you have? Surely the ghastly taste made you stop?" He questioned, as Sherlock stood puzzled at how a potion could do this.

" Well only a sip, it tasted like goblin puke! This is the students, this is the children!" She shrieked, causing the moving people in the portraits around her to cover their ears.

" Come with me, we'll get you to Madam Pompfrey, it should wear off very soon if it was only a sip now." Dumbledore said, leading the cat lady away. He glimpsed around at Sherlock and gave a sly wink, then disappeared down the moving staircases. Sherlock sighed and turned round the corner, only to bump once again, into Hermione Granger. But it was not only her this time, as Harry Potter was behind her too.

" Professor!" She gasped, her nerves giving her away to be the guilty culprit.

" Well done Miss. Granger, that was an impressive transformation you tricked her into." Sherlock said, looking down at the two who were shuffling on their feet.

" Sir-" Harry started, before Sherlock gave him a stern look. " Sherlock, this was my fault. She gave me detention and-" But he was once again interrupted by Hermione who grabbed his wrist and showed it to Sherlock.

" She's a monster, she made him write lines in his own blood! I just wanted...to pay her back because well, Harry won't complain to Dumbledore. I'm not a rebel, I just believe in justice." She stammered, holding her views as strongly as she held her books in the corridor. Sherlock examined the cut on Harry's arm, engraved on it ' I will not tell lies'. The girl was right, this was barbaric, Harry was facing his enemies from all corners.

" Well, as I said, Well done on behalf of muggles and muggle borns Miss Granger. I'm going to bed now, having never seen the pair of you after lights out." Sherlock hinted, walking away from the pair who stared after him. Hermione turned to Harry, accidentally whipping her hair into his eye briefly.

" Sorry, Harry. That Sherlock, I have a bad feeling about him." She whispered as they watched the tall, mysterious figure walk calmly away.

" Hermione he just saved you from being expelled, which, as I recall you once said was worse than death." Harry retaliated, becoming attached to the man quite quickly.

" Yes but, I just have a feeling, that's all. Like, he's not just a professor you know? There's something else." She wavered, her voice becoming softer.

Harry was yet to know Hermione was right, and that his life will soon depend on Sherlock's presence at Hogwarts.


End file.
